Researchers biopsied nicotine pouch users’ mouth lesions. Four showed dysplasia at the placement site.
A Newcastle University preprint surveyed 3,659 pouch users and assessed 33 in clinic: 45% reported oral side effects, and 4 of 10 biopsied lesions showed epithelial dysplasia exactly where pouches are parked. Not peer-reviewed; causality not established.
A research team at Newcastle University has published the most detailed look yet at what happens inside the mouths of nicotine pouch users — and it includes something no study had shown before: biopsy-confirmed oral epithelial dysplasia (a tissue change that can carry a raised risk of turning cancerous) in lesions found exactly where users park their pouches. The work is a preprint posted on medRxiv on 5 October 2026, so it has not been through peer review yet.
What the study found
The team ran three investigations in parallel:
- A survey of 3,659 nicotine pouch users — 89% male, 78% aged 16 to 22. 45% reported at least one oral or dental side effect. The most common were gum recession (60% of those reporting effects), burning sensations (41%), white patches (30%) and dry mouth (29%). Users with higher nicotine exposure reported more side effects.
- A survey of 126 UK dental professionals. Most said they see pouch-related oral lesions in clinic; only 17% reported seeing no oral or dental effects at all.
- In-person clinical assessments of 33 users, including full oral and gum examinations. Ten lesions were biopsied: six showed hyperkeratosis (thickened keratin layer) and four showed oral epithelial dysplasia — three mild, one moderate. All dysplastic lesions sat at pouch placement sites.
There is one genuinely encouraging detail. In two cases, clinical follow-up showed partial or complete resolution of lesions after the user stopped using pouches. The study's own framing is that "at least some NP-associated oral changes may be reversible."
What it can and cannot tell you
Three caveats matter before drawing conclusions:
- It is a preprint. No peer review yet; numbers and interpretations can change.
- Causality is not established. The authors say so explicitly. The dysplasia cases are the first of their kind reported for pouches, not proof that pouches cause cancer or confirm that pouch placement alone produced the changes.
- The user survey was self-selected, so the 45% side-effect figure may not represent all pouch users — people with problems are more likely to respond. Notably, the clinical gum assessments of the 33 in-person users actually showed generally low levels of periodontal disease and recession.
The ethical approval (London - Surrey Research Ethics Committee, ref 25/LO/0816) and funding (a British Society for Oral and Dental Research award) are stated in the preprint.
Why it matters
This is the first histopathological report of dysplasia at nicotine pouch placement sites, which is exactly the kind of finding that shapes regulation and dental guidance. The authors' stated conclusion is not a ban or a scare: it is that dental professionals need to be vigilant and that urgent longitudinal research is needed to determine how common these lesions are, how they progress, and how reversible they are. For regular users, the practical takeaway currently supported by evidence is the dose signal — higher nicotine exposure tracked with more reported side effects — and the observed improvement in lesions after stopping.
PouchFinder lists nicotine strengths for each brand at PouchFinder, which is useful context for the dose finding above.